Rules of thumb/key criteria for multi-family purchase

[Robin Schumacher]

The investment materials I've read so far have given me a good handle on the key criteria to use for single family investment purchases (e.g. 3brdm, 2bath, place for storage/growth, etc.), but they don't do so well with multi-family. What are the key checklist items for purchasing 4-8plex properties? For example, should each unit have a minimum of 2bdrm or do such things not universally apply to all units or the building in general?

Thanks in advance.